Growth in the building of canals was made possible by

The answer is: Improvements in engineering methods.

In order to build a canal, advanced engineering methods are needed to creates dams and locks so we can  stretches the slack water levels of the canals. This would be impossible with traditional engineering method.

Beside that, advanced engineering methods also reduce the time needed for the projects and reduce the cost of building the canals.

industry had made the u.s. the richest nation in the world at this time. the second industrial revolution caused growth in industry and transportation, which allowed increased trade between nations.